Resistance to amitraz and flumethrin inVarroa destructorpopulations from Veracruz, Mexico

SUMMARYDose response curves were determined for amitraz and flumethrin for Varroa destructor collected near Veracruz city, Mexico. Both pesticides were sprayed at known concentrations on female mites using a Burgerjon's tower. Probit analysis was performed to calculate mean lethal concentrations (LC50). We estimated the LC50 for amitraz to be 0.526 mg/litre; this estimate is 2.3-times higher than the LC50 baseline established nine years earlier in Mexico. The LC50 for flumethrin was estimated as 0.286 mg/litre, 327-times higher than the LC50 baseline, suggesting the development of resistance.